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DRV8834 EVM

Nir Gazit
Prodigy 60 points
Other Parts Discussed in Thread: DRV8834, DRV8834EVM, ENERGIA

Hi

I've been trying to use the EVM with a DC motor or with a stepper motor (connecting it to both AOUT and BOUT) but failed to make them work.

I see the AENBL pin go high (or pulses on the STEP when working with a stepper motor) but the motor won't move. When using the DC motor, it seems to work when connecting it directly to DC but it didn't work using the DRV8834. I've connected a probe to AOUT1/2 but couldn't see and voltage on these pins. I double checked the configurations of AVREF and BVREF

Can someone please help?

  • 0
    TI__Guru** 114905 points
    Hi Nir,

    What is the VREF setting?

    Please look at the outputs pins. If current regulation is being used, the outputs may be toggling between one high/one low and both low. When both low, the outputs should switch back to one high/one low in less than 25us. This may not create enough current to drive the motor. Increasing VREF could help.

    If the outputs do not look like the description above, the device may be entering overcurrent protection. The nFAULT pin should assert and the outputs are disabled for approximately 1.2ms. If there is a capacitor connected between the outputs (sometimes inside the motor assembly), this can cause the overcurrent.

    If the outputs are disabled for more than 10ms and the nFAULT pin is asserted, this could be an indication of overtemperature.

    Undervoltage is another possibility, which is indicated by nFAULT and the disabled outputs.

    Please note there are no protection features when connecting the motor directly to a DC supply.
  • 0 in reply to Rick Duncan
    Prodigy 60 points
    Hey
    I don't see anything on the output pins at all. They stay at low all the time. I tried changing between different VREF settings but still nothing happens.
  • 0 in reply to Nir Gazit
    TI__Guru** 114905 points
    Hi Nir,

    What do you see on the outputs if you disconnect the motor?

    What is your system voltage?

    Have you checked the nSLEEP pin to confirm the device should be awake?
  • 0 in reply to Rick Duncan
    Prodigy 60 points
    Hi
    I don't see anything on the outputs. VM is connected to 5V. nSLEEP is low.
  • 0 in reply to Nir Gazit
    TI__Guru** 114905 points
    Hi Nir,

    nSLEEP should be high for the outputs to be active. There could be a problem with the GUI connection.

    Assuming you are using the GUI, please make sure the correct com port is selected in the pulldown menu and then click Connect.

    Then toggle nSLEEP or M1 to confirm correct connections.
  • 0 in reply to Rick Duncan
    Prodigy 60 points

    Hi,

    Thanks. Apparently that was the problem. Solved now.

  • 0 in reply to Nir Gazit
    TI__Guru** 114905 points
    Hi Nir,

    I saw your post about the source code but cannot access it.

    The code can be found in the Hardware Files of the DRV8834EVM folder ( www.ti.com/.../slvc589 )

    There is additional acceleration/deceleration code available in the Energia libraries. Please evaluate those also. The link is energia.nu/.../